The present invention relates to a mixer for delivering a mixture of two gases G.sub.1 and G.sub.2 in proportions by volume of X/100 and (100 X)/100 respectively, of the kind comprising a circuit for each of the said gases, connected to a circuit for the mixture.
There are special applications for which the lowest proportion of one gas by comparison with the other should be adhered to strictly, and this applies in the case of anaesthesia in which the safety of operation of the oxygen and nitrous oxide mixers represents an essential condition. The mixture supplied should contain a minimum of 21% of oxygen so that it is not hypo-oxidic.
It is an object of the invention to prevent or minimise delivery of a mixture containing less than X/100 of G.sub.1 gas (oxygen), and to limit the flow rate of the gas G.sub.2 (nitrous oxide) to a particular value notwithstanding the adjustment of the feed rates of the said gases.